Coronary arteries can become narrowed over time, such as when a build up of cholesterol and cellular debris causes a plaque to form. These narrowed vessels are commonly treated with the use of a stent to rexpand the vessel lumen. These stents are typically metal, meshlike and tubular in shape and can be expanded from a collapsed position on a balloon to an expanded position in the vessel when deployed. Typically, the stent is inserted through a vessel in its collapsed position until the stent reaches the location where the narrowing of the vessel occurs. Once at the desired location, the stent can be expanded by expanding the balloon to force open the vessel, allowing blood to continue to flow through the vessel. The stent acts as scaffolding to overcome the elastic recoil of the vessel wall and becomes incorporated into the vessel wall when a new lining grows over it. Typically, the stent is moved to the site in question, crimped on a balloon catheter. The balloon catheter is then inflated to expand the stent.
This method is used when the narrowing occurs along the main vessel or branch of the main vessel. However, when the narrowing occurs where one vessel branches away from another (a bifurcation), this presents additional challenges and requires additional techniques to be used to deal with the narrowing. One of these techniques is what is commonly referred to as the “kissing balloon” technique. It involves placing a stent in the main vessel so it runs across the opening to the branch vessel. Once the stent is in place, two guide wires can be placed (one in the main vessel, one partly down the main vessel, then down the branch vessel) with each guide wire having a balloon catheter running along each guide wire. Where the branch vessel opens into the main vessel, the balloons can be inflated, with one of the balloons used to further expand the stent, while the other balloon is used to balloon through the sidewall of the stent and into the branch vessel, maintaining its patency. However, this kissing balloon technique has its drawbacks. It typically results in damage to the vessel branching off the main vessel due to the expansion of the balloon against the branch vessel. This will increase the risk of renarrowing the side branch vessel in the weeks to months after the procedure.